What does "kick it up into high gear" mean? Is "kick it up into something" an idiom?
You are correct. This is an idiom, though I think it is more of an American one. “Kick it into high gear” is usually used to mean that we start working hard and, or faster on some task, plan or activity. For example, if you have a deadline coming up and still have a lot to do, you really have to “kick it into high gear” to get everything done on time. It comes from the action when cars shift to a higher gear so they can drive faster. Ex: If we want to meet the project deadline we have to kick it into high gear. Ex: Let's kick it into high gear and see if we can finish everything tonight.